TASTE OF GRANIVOROUS BIRDS. 126 



concerning the use of these pebbles, so long- agitated 

 by authors. It appears that they are not at all neces- 

 sary to the trituration of the firmest food, or the 

 hardest foreign substances, contrary to the opinion of 

 many anatomists and physiologists, as well ancient 

 as modern ; I will not however deny, that when put 

 in motion by the gastric muscles, they are capable of 

 producing some effects on the contents of the sto- 

 mach*." Blumeribach, however, denies both these 

 facts and Spallanzani's conclusion, of the stones being 

 swallowed without design, from mere stupidity ; and 

 asserts that " these stones are so essential to due di- 

 gestion that birds grow lean without them, although 

 they may be most copiously supplied with food I;" 

 a fact attested also by Dr. BostockJ. 



Without deciding this contested point, we shall add 

 the remarks of our distinguished physiologist, John 

 Hunter, upon the opinion of Spallanzani. " In con- 

 sidering," says he, " the strength of the gizzard, and 

 its probable effects when compared with the human 

 stomach, it must appear that the gizzard is in itself 

 very fit for trituration. We are not, however, to 

 conclude that stones are entirely useless; for 'if we 

 compare the strength of the muscles of the jaws of 

 animals who masticate their food, with those of birds 

 who do not, we shall say that the parts are well 

 calculated for the, purpose of mastication ; yet we are 

 not from thence to infer that the teeth in such jaws 

 are useless, even although we have proof that the 

 gums do the business when the teeth are gone. If 

 stones are of use, which we may reasonably conclude 

 they are, birds have an advantage over animals having 

 teeth, so far as stones are always to be found, while 

 the teeth are not renewed. If we constantly find in 



* Dissertations, i. 26. t Comp. Anat. 100. 



J Physiology, iii. 458, note. 



